Magnetic receiver



Sept. 12, 1950 H. E. HANSON 2,522,266

MAGNETIC RECEIVER Filed May 25, 1948 2FIG. l H62 43 4| 4o 7 "1- as '5 '9 36 IO 0 3 32 4 I I 3B 42 1 H E 4,: I 26 25 3| 20 Is 5 l 26 I7 G '8 f: '3 l5 24/ a1 4 48 2 I5 42 m .16 i I4 FIG. 3

l7 5 9 a y E I5 I i 24 J as F JG. 5 10 4 W INVENTOR. 9-10 HARVEY HANSON 32 5?, a

AGENT Patented Sept. 12, 1950 UNITED STATES PATENT OFFICE v ,mona r r o ifi omvcn v I Q Harvey Hanson;- Chicago, 111., assignor to Beltone Hearing Aid-"(lo Chicago, 111.; a corporation of -Illin'ois ,n ucaticnMaycs, wiaseriai No. 29,081

6 Claims. (01. 179-117) [This invention relates" to midget receivers for hearing aids.

:One of the objects .of the invention is to pro:-

videea receiver for hearingaids which is extremely small in size but despite its small size. is of very reat efficiency.

"During recent ,years the manufacturers of hearing, aidshave turned more andmore to what.

is called. .a single unit instrument wherein the microphone; an electron tube amplifier and ;the

batteries therefor are all placed in .alcom'mon housing small enough tocbe worn .inan ordinary vest pocket. At present, wearable hearing aids are built almost exclusively as single unit .instril- 'ments, the size of thebatteriesrused therein having become ever smaller. In view thereof, it isanv object of this invention to provide a magnetic receiver '.for hearing .aidswhich will assure a highly satisfactory Iacoustic'output also with hearingaids using theflsmallest size batteries available; at present for hearing aid purposes.

"Another object ofthe inventioniis to provide amagneticmidget receiver for hearingaids ,hav-

ing relatively low alternating current reluctance. LA further object of .thelinventionis to provide in a magnetic midget receiver a source ofeperma nent magnetism of low ,A. C. reluctance by arranging the permanently magnetic. material .in such a form as to afforda large effective surface forthe volume of magnetic .materialused. v

I A further object of the .inventionis to provide a magnetic midget receiver having two-permanentmagnets connected in parallel by means of connecting members which for-mpart-oftworpole pieces each carrying an energizing coil.

n is a further object r the inventiontc -providecin a magnetic. midget receiver two :perma nent magnets for the purposeof increasingthe efi'ectivesurface area of said permancntmag,

nets, the latter being placed into. the A.,C..magnetic circuit at such points that reductionof the A. C, reluctance will result due to the increased leakagesuch two magnets willeaiford as compared with a single, permanent magnet'having the same weightas the twomagnets. together,

Another object of the invention is to provide a :magnetic midget receiver whereinthe permanentmagnets and the pole pieccsare maintained at their proper places within thehousing without resort to soldering or screws for. co'nnectingthe permanent magnetsand the polepieces.

.Afurther object of the invention is-to: provide a magnetic midget receiver whereintheperma v nent magnets and the pole piecesnas well as the socket which receives the plug coming from the amplifier of the hearingaid instrument are held in their proper relative positions by means of shaping these parts in such a manner that'each of them interlocks with at least one other of the parts mentioned. v

r A further object of the invention is to provide a magnetic midget receiver wherein the permanent magnets and the pole pieces which carry h energizing coils are held within a housing by 7 means of a non-magnetic retaining member without resort to soldering or screws for connecting thepermanent magnets and the pole pieces-so that upon removal of said retaining member the elementsof the magnetic drive of the receiver can be easily and separately removed .from the housing, such as for purposes of inspection .or repair.

Still. another object of the inventionresides in I the provision in a magneticmidget receiver which has a diaphragm carrying an armature for the 'pole pieces of a member of highly permeable.ma-'

of the figure showing a section along the line 3--.-3..in Fig. 1;, I

Fig. 4 is a section on the lines 4--4 in Fig.3; and

- Fig. 51s a section on the line 5-.-5.in Fig. 4.

A cup shaped housing I001 nonma netic material has a bottom II, which may be of curved shape, a cylindrical side wall [2 andla .side opening l3. Fitting over an undercut portion 16 on the outside of the cylindrical wall l2 of the housing lllis a cap is which has acentral opening ll surrounded by a substantially lfrusto-conicalv extension I8. A washer [9, preferably made of a plasticmaterial, e, g. viny1ite,. is placedaround the extension H3- so as to rest against the surface I 5 of the capl5. The parts 48, I9 serve forvthe attachment of the so-calledear mold (not shown) adapted to be inserted vinto the ear of the user.

Fitting into a recess 27 of the inner side of the bottom H of the housing ill in such a-manrier as to face with one open side the inner endlofthe opening l3. in the side wall l2'of the housing is a socket 20 containing two contact sleeves :21, 22 adapted to receive'two contact pins 23 of a plug Mwhichin the usual manner forms part of a connection to the output terminals'of the hearingJaid-instrument women the body of the user. The contactsleeves 2.l, 22 are providedeach-with a prOng; 24 for connection with :oneiof two enerj lzing coils 25,- 26. "Each coil 25,26 is carried by Establishin two parallel magnetic bridges be V tween the two pole pieces 30 and SI are two permanent magnets 33 and 3'l.- While these two permanent magnets, in order to fulfill their functions as bridges between the two pole pieces, might be of such lengths only as to fit abuttingly between the pole pieces, it is preferable from the point of view of magnetic efficiency to make these permanent magnets as long as the dimensions of the housing ll] permit. In accordance with this consideration, the drawing shows permanent magnets 36, 3'! which extend across the entire widths of the pole pieces 30, 3! and are held in contact with the latter by means to be described later.' An insulating strip 48 serves to insulate the socket contacts 24 from the permanent magnet 31.

, Supported by a rim 42 of the housing in is the peripheral edge of a diaphragm 43 carrying at its central portion a disk-shaped piece 44 serving as an armature for the pole pieces 30, 3|. The armature 34, which consists of highly permeable material, e. g. soft iron, is arranged on that side of the diaphragm 43 which looks away from the pole pieces 3i], 3!, whereas the side of the diaphragm looking towards these pole pieces is flat.

It will be noted that in the arrangement shown the metallic parts of the magnetic paths are common for both the A.-C. magnetic circuit and the D. C. magnetic circuit. Due to the fact that two permanent magnets 36, 31 are used which are connected by means of the plate-shaped members 32 ,of the polepieces 30, 3i, the effective surface of these magnets is greater than would be the I effective surface of a single magnet of a volume equal to the combined volumes of the two magnets 3t, 31. Thereby there is provided for the A.-C. magnetic flux a greater leakage and thereby a lower A.-C. reluctance of the system, which,

in turn means an increased output of the receiver. In order to reduce still further the reluctance of the system to the A.-C. magnetic flux the pole pieces 30, 3| are arranged as close to each other as the presence of the socket 23 in the receiver will permit, that is to say, these pole pieces are arranged so as to directly abut said socket and partly to overlap it, as is best seen in Fig. 3.

The provision of the permanent magnetism in the'form of two segmental magnets 36 and 31 is not only beneficial from the viewpoint of reducing the A.-C. reluctance but also from'the viewpoint of the utilization of the space available within the housing l0. By arranging two segmental magnets adjacent to two diametrically opposite portions of the cylindrical side wall of the housing [0, it becomes possible to accommodate the socket, the pole pieces and the energizing coils within a housing of smaller diameter than would be necessary if a single permanent magnetof the same energy product as the two magnets 36, 3'! were used.

The system as described thus far develops a strong magnetic flux across the gap between the diaphragm 43 and the end surfaces of the arms 33' of the pole pieces 33, Si. The density of this flux is substantially increased by the arrangement within the cap I5 of a member 45 of highly 4 example shown this member 45 is in the form of a ring sunk into a recess provided in;the inner surface of'thef cap it so as to be fiush'with that surface. While this member 45 is magnetically in parallel with the armature ill it will be noted that, incontrast to this armature, it does not vary its relative position to the pole pieces 30, 3| but is stationary in the cap l5.

. Good contact between the permanent magnets 36, 31 and the plate-shaped members 33 of the pole ieces 30, 3| is necessary. In connection with magnetic midget receivers such good contact was heretofore sought to be achieved by either screwing together or soldering together pole piece and permanent magnet. The construction according to the present invention avoids such connecting means between pole pieces and permanent magnets and uses instead an arrangement wherein each of the parts:. housing l0, socket 20, pole pieces 30, 3| and.

portions 33, 34 and 35 and the plate-shaped members 32 of the pole pieces 30 and 3! have correspondingly recessed portions 29, 34' ,and 35'. Thus, each of the members 32 of the two pole pieces 30 and 3! fits into a cavity delimited by the projecting and recessed portions of the, inner wall of the housing [0 and by thestaggeredoutside wall of the socket in. Of thepermanent magnets 36, 31, which are both flat at their top side looking towards the cap 15, the

opposite side of the magnet 36 has a projecting portion 38 which in the assembled position of the parts fits between the inner edges of the members 32 of two pole pieces 30, 3l, whereas the bottom side of the magnet 31 has a depressed portion 39 to fit over the raised portion 35 of the bottom of the housing l0. With the excep tion of the projecting portion 38 the magnet 35 rests flush against the upper surface of the members 32 of the two pole pieces 30, 3| and like wise the permanent magnet 31, with the exception of the depressed portion 39, rests upon the upper surface of the members 32 of the two pole pieces 30, 3|, the arrangement being such that all the four contact surfaces existing between the two permanent magnets and the two pole pieces are situated in a common plane.

The aforementioned retaining member 40 is in the form of a ring having an outside thread that can be threaded into an inside thread 4| in the cylindrical wall l2 of the housing In.

When the ring 40 is threaded in sufficiently it will hold the pole pieces 30, 3| and the permanent magnets 36, 31 in contact with each other and at their proper places relative to each other and to the housing H) as well as to the socket 20 by virtue of the interlocking arrangement of the parts above described. Upon unscrewing the ring 40, the elements contained in the housing [0 can be taken out without any further unscrewing operation or breaking of solder connections." It will be appreciated that the absence of solder connections not only facilitates the assembly and disassembly of the receiver and the achievement of greater uniformitybetw'een the individual units of the series produced;'but that also space is saved and that additional re- As an example of such an, interlocking arrangement the drawing shows the side walls of the socket ID as being provided with a step 21 whereas the housing It! has projecting luctance is removed which the insertion of a soldering point creates in a magnetic path formed by magnetic material.

While I have shown in the drawing one particular embodiment of the invention, I desire it to be understood that this embodiment has been given by way of example only and that various changes, modifications, and re-arrangements of parts may be carried out without departing from the spirit of the invention or the scope of the appended claims.

What I claim is:

1. A magnetic midget receiver for hearing aids, comprising a cup-shaped housing, a socket adapted to receive a plug extending into said housing, two pole pieces separated from each other by said socket, each of said pole pieces having an arm carrying an energizing coil and a substantially plate-shaped member extending substantially perpendicularly to said arm, one surface of the plate-shaped members of both said pole pieces extending in a common plane, two permanent magnets extending across both said pole pieces and being in contact therewith, and each of said parts: housing, socket, pole pieces, and permanent magnets being shaped for interlocking with at least one other of these parts.

2. A magnetic midget receiver for hearing aids, comprising a housing, two pole pieces arranged at a distance from each other, each of said pole pieces having an arm extending axially through an energizing coil and a substantially plateshaped member extendin substantially perpendicularly to said arm, one surface of theplateshaped members of both said pole pieces extending in a common plane, two permanent magnets arranged at a distance from each other so as to have said pole piece arms between them and extending each across said plate-shaped members of both said pole pieces, so as to rest removably 1 thereon said pole pieces and said permanent magnets having relatively projecting and recessed portions for interlocking with each other, and a non-magnetic retainer element for holding said interlocking pole pieces and said permanent magnets within said housing and in con tact with each other.

3. A magnetic midget receiver for hearing aids, comprising a cup-shaped housing, a socket adapted to receive a plug extending into said housing, two pole pieces separated from each other by said socket, each of said pole pieces having an arm carrying an energizing coil and a plate-shaped member extending substantially perpendicularly to said arm, one surface of the plate-shaped members of both said pole pieces extending in a common plane, two permanent magnets arranged at a distance from each other so as to have said pole piece arms between them and extending each across said plate-shaped members of both said pole pieces, each of said parts: housing, sockets, pole pieces and perma nent magnets being shaped for interlocking with at least one other of these parts, and a non-magnetic retainer ring for holding said pole pieces and said permanent magnets within said housing and in contact with each other at said surfaces in said common plane.

4. A magnetic midget receiver for hearing aids, comprising a cup-shaped housing having a rim, a socket adapted to receive a plug extending into said housing, two pole pieces separated from each 6 other by said socket, each of said pole pieces having an arm carrying an energizing coil and a substantially plate-shaped member extending substantially perpendicularly to said arm, one surface of the plate-shaped members of both said pole pieces extending in a common plane, two permanent magnets extending across both said pole pieces and being in contact therewith, each of said parts: housing, socket, pole pieces and 1 permanent magnets being shaped for interlocking with at least one other of these parts, and a diaphragm adapted to rest with its edge portion upon the rim of said housing.

5. A magnetic midget receiver for hearing aids,

' comprising a cup-shaped housing having a rim,

a socket adapted to receive a plug extending into said housing, two pole pieces separated from each other by said socket, each of said pole pieces having an arm carrying an energizing coil and a substantially plate-shaped member extending substantially perpendicularly to said arm, one surface of the plate-shaped members of both said pole pieces extending in a common plane, two permanent magnets extending across both said pole pieces and being in contact therewith, each of said parts: housing, socket, pole pieces and permanent magnets being shaped for interlocking with at least one other of these parts, a diaphragm supported at its edge portion by said rim and carrying a central armature for said pole pieces, and a member of highly permeable material within said cap for forming a magnetic path in parallel to the magnetic path through said armature on said diaphragm.

6. A magnetic midget receiver for hearing aids, comprising a cup-shaped housing, having a rim, a socket adapted to receive a plug extending into said housing, two pole pieces separated from each other by said socket, each of said pole pieces having an arm carrying an energizing coil and a substantially plate-shaped member extending substantially perpendicularly to said arm, one

I surface of the plate-shaped members of both said pole pieces extending in a common plane, two

permanent magnets extending across both said through said armature on said diaphragm.

HARVEY E. HANSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,628,383 Young May 10, 1927 2,069,817 Clarke Feb. 9, 1937 2,086,630 Miner July 13, 1937 2,141,820 Parcdes Dec. 27, 1938 2,231,084 Morrison et a1. Feb. 11, 1941 2,249,158 Morrison July 15, 1941 2,371,453 Linell Mar. 13, 1945 Pearson Jan. 3, 1950 

